There are conventionally known wiring units in which a wire harness is fixed to a plate. For example, in the wiring unit that is disclosed in Patent Document 1 (JP 2014-199071A) below, a wire harness is mounted on a plate and is fixed to the plate at a plurality of positions using cable ties. A cable tie is passed through a pair of pass-through holes that are formed penetrating the plate and is locked to the back surface side of the plate, to tie up the wire harness on the top surface side of the plate.